INTERNATIONAL JOURNAL O F
SYSTEMATIC BACTERIOLOGY
A p r i l 1966
pp. 135-142
Vol. 16, No. 2
MINUTES OF LAMS SUBCOMMITTEE ON
TAXONOMY O F VIBRIOS
The IAMS Subcommittee on Taxonomy of Vibrios m e t on
J a n u a r y 29, 1965 i n Honolulu, Hawaii during the occasion
of the Symposium on Cholera R e s e a r c h held a t t h e E a s t West Center a t the University of Hawaii. M e m b e r s p r e s e n t
w e r e Dr. Rudolph Hugh (Chairman), Dr. John C. F e e l e y
Dr.
( S e c r e t a r y ) , Dr. S. Mukerjee, and Dr. R. Sakazaki.
Dr. D. L, S h r i v a s t a v a
C h a r l e s R. Manclark was absent.
attended a s a n o b s e r v e r a t the invitation of the Chairman.
The following m a t t e r s w e r e d i s c u s s e d and action taken
a s follows:
1. The Subcommittee a g r e e d unanimously t o support the
p r o p o s a l by Hugh (Int. Bull. Bact. Nom. and Taxon. 1 4 ~ 8 7 101, 1964) that ATCC s t r a i n 14035 (NCTC 8021) be designated the neotype s t r a i n of Vibrio cholerae Pacini 1854.
2. The Subcommittee a g r e e d unanimously t o support the
proposal by Hugh (Int. Bull. Bact. Nom. and Taxon. 2 - 6 1 68, 1965) that ATCC s t r a i n 14033(NCTC 8457) be designated
the neotype s t r a i n of Vibrio e l t o r P r i b r a m 1933.
3. The Subcommittee d i s c u s s e d at s o m e length t h e question of whether Vibrio cholerae and Vibrio e l t o r should be
recognized a s two distinct s p e c i e s o r a s a single species. It
was noted that historically 1.e l t o r ( o r the so-called " E l T o r
vibrio") was differentiated f r o m ,V. cholerae solely on the
b a s i s of the haemolytic p r o p e r t i e s of the f o r m e r . Difficult i e s with detection of haemolytic activity have led t o t h e utilization of other differential c r i t e r i a such as bacteriophage
sensitivity, chicken-erythrocyte agglutination, Voges-Prosk a u e r reactivity, polymixin B sensitivity, growth i n t r y p s i n
broth, soda-agglutination, and sublimate precipitation ( s e
Felsenfeld, Bacteriol. Rev. 2 : 7 2 - 8 6 , 1964; Hugh, Int. Bull.
Bact. Nom. and Taxon. 2 : 6 1 - 8 8 , 1965). The p r o b l e m i s
now complicated by t h e appearance of s t r a i n s which a r e
partially o r completely lacking i n haemolytic activity but
have other c h a r a c t e r i s t i c s of 1.eltor. The l a t t e r a r e commonly r e g a r d e d by many w o r k e r s a s "nonhaemolytic" 1.
e l t o r . In any event, t h e r e is no longer any question of the
ability of the E l T o r vibrio t o cause epidemic cholera i n man.
D r s . Hugh, F e e l e y , and Sakazaki held t h e view t h a t t h e
d e s c r i b e d differences between Vibrio cholerae and 1. e l t o r
a r e insufficient f o r the recognition of the two o r g a n i s m s as
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distinct s p ec i e s , although they a r e of unquestionable epide mi 010g i c s ignif i c a n ce
Dr. Mukerjee a g re e d that t h e o rg a n is m s w e r e v e r y similar, but e x p re s s e d the view that differences should be indicated i n s o m e way i n nomenclature. He indicated that he
held no s t r o n g feelings as t o whether the or gani s m s w e r e
called ,V. e l t o r o r 1. cholerae type e l t o r , o r by s ome similar designation.
A minority re p o rt by Dr. Mukerjee i s appended t o t h e s e minutes.
4. The Subcommittee recommended the following provisional description of the genus Vibrio:
.
Gram-negative; asporogenous rods with a single rigid
curve o r straight ro d s ; single polar flagellum; indophenol oxidase positive; produce acidity without gas
f r o m dextrose. Acidity f r o m dextrose is produced by
the Embden-Meye rhof glycolytic pathway.
It was recognized that this provisional description will
not differentiate o rg a n i s m s i n the genus Vibrio f r o m anaerogenic s t r a i n s of Aeromonas, and that f ur t her studies
will be needed t o r e a c h a g re e m e n t on how this definition
should be emended to e i t h e r include o r exclude the l a t t e r
similar organisms.
Nevertheless, the Subcommittee noted
that the definition effectively excludes or gani s m s of the gene r a Comamonas and Pseudomonas which have been classified
a s Vibrio on t h e b a s i s of s o m a t i c curvature.
It was a l s o recognized that the anaerobic and m i c r o a e r o philic o r g a ni s m s such as Vibrio fetus a r e of questionable
relation t o other m e m b e r s of the genus and that recommendations f o r t h e i r classification elsewhere have been made
(vide Sebald and Ve'ron, Ann, Inst. P a s t e u r , %5:897-910,
1963). Since Dr. Manclark, who i s m o r e familiar with
t h e s e o r g a n i s m s , was absent, no recommendations w e r e
made.
5. The t e r m "xibrio" (not capitalized) is the common o r
v e r n a c u l a r name fo r the genus named Vibrio and i s used t o
r e f e r t o a b a c t e ri u m o r s p e c i e s i n t h i s genus. The subcomm i t t e e could not recommend the u s e of the t e r m vibrio t o
r e f e r t o all b a c t e ri a with a single somatic curve.
Bact er i a
with a single s o m a t i c curve m a y belong t o gener a other than
Vibrio (viz. Aeromonas, Pseudomonas, Comamonas).
6 . The Subcommittee recognized that the s peci es Vibrio
cholerae and Vibrio e l t o r could both be divided. into Ogawa
and Inaba eerotypes, and noted that Feel ey (J. Bacteriol.
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137
89:665-670,
1965)had proposeddivision of the single s peci es
Vibrio cholerae (including V. e l t o r ) into types based on phage
IV sensitivity, chicken-erythrocyte agglutination, tube and
plate hemolysis, and Voges-Proskauer activity.
7. Dr. Hugh was elected Chairman and Dr. F e e l e y was
elected S e c r e t a r y t o s e r v e until the next meeting of t h e s u b committee
.
Respectfully submitted,
John C. Feel ey, Ph. D.
Secretary
Minority Report by Dr. S. Mukerjee
Within a given b a c t e ri a l genus it is only to be expected
that s i m i l a r i t i e s i n biochemical, antigenic and other char My opinion is
acte r i s t i c s will outnumber the difference s.
that the c r i t e r i a f o r s p e c i e s differentiation should not be
n u m e r i c a l but qualitative i n the s e n s e whether the differe n c e s a r e of fundamental biological importance. The principal considerations which incline m e t o classify 1. cholerae
and ,V. e l t or i n distinct s p e c i e s a r e given below i n t abul ar
form.
POINTS OF DIFFERENTIATION BETWEEN
VIBRIO CHOLERAE AND VIBRIO ELTOR
I. H i s t o r i c a l Considerations:
Vibrio cholerae h a s been known t o be as s oci at ed with
c l a s s i c a l cholera since it was first identified as the causative o r g a n i s m of cholera by Robert Koch i n 1883. It h a s
been isolated f r o m stool s a m p l e s of patients suffering f r o m
cholera which a t one t i m e s p r e a d t o m o s t countries of the
world and si n c e 1923 h a s been limited t o a few Asian countries.
F r o m 1962 c l a s s i c a l cholera i s known t o occur only
i n India and Pakistan.
Vibrio e l t o r was i s o l a t e d f o r t h e first time by Gotschlich
i n 1906 i n the E l T o r quarantine station f r o m the intestines
of patients who died of d i s e a s e s o t h e r than cholera. In fact,
the pilgrimage of that y e a r was e n t i re l y f r e e f r o m cholera.
Since then t h i s type of vibrio h a s been frequently i s ol at ed i n
the Middle E a s t countries f r o m w a t e r s o u r c e s a s well as
--
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f r o m healthy p e r s o n s o r c a s e s with symptoms of mild d i a r rhoea. T h i s type of vibrio h a s a l s o been found in other a r e a s
i n the absence of cholera E l T o r . F o r many y e a r s 1. e l t o r
was considered apathogenic o r only mildly pathogenic. T h i s
led van Loghem (1932) to r e m a r k that E l T o r d i s e a s e and
cholera a s i a t i c a should be considered different d i s e a s e s
ae tiologi cally.
In September 1937
e l t o r s t r a i n s w e r e f o r the f i r s t
t i m e isolated f r o m cholera-like c a s e s i n South Celebes i n
Indonesia where the d i s e a s e r e m a i n e d confined f o r s e v e r a l
decades. Since 1961 cholera E l T o r h a s come out of i t s
original home and h a s been spreading i n a pandemic f o r m
involving m o s t countries in the Southwest Pacific region and
i n South and Southeast Asia. Towards the end of 1963 it
e n t e r e d t h e Indo-Pakistan Subcontinent and within a y e a r
f r o m then it h a s s p r e a d t o wide a r e a s i n India and Pakistan.
In many a r e a s in the subcontinent c l a s s i c a l cholera c a s e s
have now been replaced by c h o l e r a E l T o r while i n s o m e
other a r e a s they co-exist i n mixed outbreaks.
F r o m the epidemiological point of view the two types of
cholera infections would thus a p p e a r to be distinct and have
t o be differentiated not only i n following the s p r e a d of infection but a l s o i n applying control m e a s u r e s and especially i n
choosing the appropriate vaccine f o r prophylaxis.
x.
-V.
-V. -e l t o r
cholerae
a ) Nature of outbreaks (de Moor, 1963):
High morbidity r a t e s
Low morbidity r a t e s
b) Contact c a r r i e r r a t e s :
Low
High
c) Convalescent c a r r i e r state:
S h o r t duration
Longer duration. Occasional c a s e s of convalescent c a r r i e r s a r e known
t o e x i s t in Philippines f o r
as long as 1 + y e a r s .
d ) A r e a s involved i n outbreaks a t present:
Limited t o India
Widespread i n West P a c i and P a k i s t a n
f i c and South and Southe a s t Asian countries.
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139
e ) Effect of a r t i f i c i a l immunization ( P r e l i m i n a r y r e s u l t s of
field t r i a l s )
V. cholerae vaccine affords E l T o r vaccine affords
only p a r t i a l protection
b e t t e r protection against
against c l a s s i c a l cholera.
cholera E l T o r than
cholerae vaccine.
E l T o r vaccine h a s not yet
been t e s t e d against
c l a s s i c a l cholera.
-
x.
f
i n outbreaks due to mixed infections by both
> Interaction
types of vibrios. (Mukerjee, Basu and Bhattacharya,
unpublished observations).
C a s e s of infection due t o
V. cholerae a r e soon outnumbered by those due t o
V. eltor.
-
III.
B
L
a ) Haemolytic c h a r a c t e r :
Nonhaemolytic
Cholera c a s e s due t o 2.
e l t o r m a y e i t h e r cornpletely o r p a r t l y replace
those due t o ,V. cholerae.
:
Usually haernolytic. If
nonhaemolytic, the haemolytic c h a r a c t e r i s t i c m a y be
induced by subcultures
und e r s ui t a ble conditions
(Roy and Mukerjee, 1963)
.
b) Rapid agglutination of chicken e r y t h r o c y t e s (Finkelstein
and Mukerjee, 1962)
Negative
P o sit ive
c ) Polymyxin sensitivity (Gan and Tjia, 1963)
Sen s it ive
Ins ens it i ve
d ) Soda-serum agglutination (Tanamal, 1959)
Negative
P o s itive
e ) Soda-sublimate precipitation (Tanamal, 1959)
Positive
Negative
f ) Phage sensitivity
1. Cholera typing phages (Mukerjee, 1963)
Generally sensitive t o the Generally insensitive t o
c h o l e r a typing phages and
typing phages and universally sensitive t o group IV totally r e s i s t a n t t o l y s i s
phage
by group IV phage.
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2. E l Tor typing phages (Mukerjee, 1964)
Insensitive to groups
Sensitivity patterns .
11, III, IV and V
vary 'according to the
phage-type of the strains.
phages
.
Aerobic glycolysis (Linton, Mullick and Mitra, 1936)
P o s i tive
Negative
Growth characteristics :
1. Rate of growth (Mukerjee, Basu and Bhattacharya,
unpublished record)
Low
High
2. Mutation in culture in respect to haemolytic character,
phage sensitivity and antibiotic sensitivity (Mukerjee,
1964)
Rare
Frequent
v.
3, Interaction in mixed cultures of
cholerae and 1.
eltor (Mukerjee, Basu and Bhattacharya, unpublished
observation)
In peptone water growth of 2. eltor over-grows
V. cholerae ceases within ,V. cholerae.
2 t o 4 hours and the vibrio
may soon be eliminated.
-
Pathogenicity (for humans)
All strains a r e pathogenic t o V,. eltor strains may be
pathogenic o r apathogenic.
humans. 1. cholerae cannot be isolated i n the absence Apathogenic strains can
of cholera outbreaks.
be isolated from a r e a s
f r e e from cholera outbreaks.
Toxins:
1, Soluble haemolysin
Usually present o r can be
Nil
induced
2. Lethal exotoxin for white r a t s (Boatman, 1936)
Nil
Present
k) Cell protein components (binton, Shrivastava and Mitra,
1935): Protein type I
Present
Absent
Protein type 11
P r e s ent
Absent
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Many of the d i f f e r e n c e s , which I have enumerated, a p p e a r
t o m e to be fundamental and t o sufficiently justify classification of the two vibrios into s e p a r a t e species. In particul a r , the known differences i n haemolytic c h a r a c t e r , ability
t o agglutinate chicken e r y t h r o c y t e s , sensitivity to polymyxin
and chemical composition of the c e l l s point t o significant
differences i n t h e i r biochemical potentialities.
The difference i n the metabolic p a t t e r n of the two groups of vibrios,
namely the p e r s i s t e n c e of glycolysis under a e r o b i c condition
in
cholerae i n c o n t r a s t t o i t s absence in 1. e l t o r is a
qualitative difference of c r i t i c a l importance since i t affects
t h e i r capacity f o r s u r v i v a l under a d v e r s e nutrient conditions.
The interaction observed i n mixed c u l t u r e s suggests a n antoganism between 3. cholerae and 1. e l t o r , which is h a r d l y
expected i n s t r a i n s belonging t o the s a m e species. Differe n c e s i n phage-sensitivity should a l s o be taken into account,
since they suggest a difference at the u l t r a - s t r u c t u r a l o r
m o l e c u l a r level.
The epidemiological manifestations of a n infectious dise a s e a r e closely r e l a t e d t o the physiological p r o p e r t i e s of
i t s causative organisms. While p r a c t i c a l advantages r e l a t e d
t o epidemiological considerations m a y not be taken a s e s s e n t i a l c r i t e r i a f o r purposes of b a c t e r i a l classification,
such advantages s u r e l y provide valuable support t o a s c h e m e
based on s t r i c t l y biological considerations. To my thinking,
the known differences i n the biological c h a r a c t e r i s t i c s of
the two types of vibrios go pari p a s s u with differences i n
clinical and epidemiological manifestations and taken together provide a sound argument i n favour of continuing the
p r e s e n t p r a c t i c e of differentiating the two groups of v i b r i o s
into distinct species. As t h e number of s p e c i e s recognisable among agglutinable vibrios a r e limited t o two only,
t h e r e is a l s o no question of any complications a r i s i n g f r o m
a multiplicity of s p e c i e s being included i n this genus, as i n
Salmonella.
v.
REFERENCES
Boatman, T. P. J. 1936. T h e s i s , A m s t e r d a m (Quoted by
de Moor, 1963).
Finkelstein, R. A. and S. Mukerjee. 1963. P r o c . SOC.
Exptl. Biol. Med. l&:335.
Gan, K. H. and S. K. Tjia. 1963. Amer. J o u r . Hyg. 77:
184.
-
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K r a u s , R. and R. P r i b r a m . 1905. Wien Klin. Wschr. 1 8 :
999.
Linton, R. W . , B. N. M i t r a , and D. N. Mullick. 1936.
Indian J o u r . Med. Res. 2 : 5 8 9 .
, D. L. S h r i v a s t a v a , and B. N. Mitra. 1935. Indian
J o u r . Med. Res. %:633.
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